After a study of various existing de-excitation methods of generators， a new method of using the linear resistor and nonlinear resistor together as the de-excitation resistance is presented. The simulation results show that the method proposed has helped increase the speed of de-excitation compared with the linear resistor. At the same time， it can improve the de-excitation reliability when a ZnO nonlinear resistor is adopted， reducing the maintenance workload. This method has been adopted in a de-excitation system of 600 MW steam turbo-generator.